In manufacturing processes of semiconductor devices, liquid crystal display devices, and the like, a circuit pattern is transferred to a resist layer after a known lithography process, and by performing processing such as etching via the resist pattern, the circuit pattern is transferred to a predetermined material film (pattern forming process). Then, by repeatedly executing the pattern forming process many times, the circuit patterns of various material films are stacked on a substrate (a semiconductor wafer or a liquid crystal substrate), whereby circuits of the semiconductor device or the liquid crystal display device are formed.
Further, in the above-described manufacturing processes, for accurate overlay of the circuit patterns of the various material films (for improving a product yield), detection of positional discrepancy of the resist pattern on the substrate follows the lithography process and precedes the processing process, during each of the pattern forming processes (see, for example, Japanese Unexamined Patent Application Publication No. Hei 11-31229). This is overlay inspection of a circuit pattern of a base layer formed in an immediately preceding pattern forming process (hereinafter, referred to as a “base pattern”) and the resist pattern. The result of the overlay inspection is used for quality judgment of the substrate and so on.
Generally, the registration detection is performed in a stand-alone apparatus independent from a lithography system (including an exposure apparatus). Therefore, substrates as detection objects after passing through the lithography process are transported to a registration detection apparatus while put in a transport container such as a cassette (that is, in a unit of lot). Then, in the registration detection apparatus, part of the substrates in the lot are sampled to undergo the registration detection, and the result of the registration detection is outputted in a unit of lot. Thereafter, quality of the substrates is judged in a unit of lot, and the substrates are transported in a unit of lot to a subsequent process (processing process or the like if judged as good, or to a reproduction process or a discard process if judged as bad.
Further, the result of the registration detection for some lot A is not only used for the quality judgment of the lot A but also fed back to the exposure process in the lithography process to be used for the correction of the exposure process for a subsequent lot B (the same product name and process name as those of the lot A), in order to improve a nondefective ratio of the subsequent lot B.
The correction of the exposure process is processing to finely adjust parts (an alignment system, an AF system, and so on) of the exposure apparatus in advance to reduce discrepancy in position and size between a latent image of a circuit pattern formed on a mask (reticle) and a base pattern (hereinafter, referred to as a “process offset”) when the latent image is imaged on a resist layer. The process offset of the exposure process varies little by little in accordance with a time-dependent change of the parts of the exposure apparatus and also varies depending on the state of the base layer of each substrate. Therefore, to avoid an increase in the process offset, the correction of the exposure process is required.
As a result of the correction of the exposure process, a latent image with a small process offset is imaged on the resist layer in the exposure process for the subsequent lot B. Then, after the development process, a resist pattern according to the latent image is formed on the base pattern, and the registration state of the resist pattern in the subsequent lot B also becomes good. The result of the registration detection for the lot B is fed back to the exposure process to be used for the correction of the exposure process for a subsequent lot C, similarly to the above.
In this manner, conventionally, the detection result outputted in a unit of lot from the stand-alone registration detection apparatus is fed back to the exposure process, and based on the result of the registration detection on some lot, the exposure process for a subsequent lot is corrected, and such correction of the exposure process is repeated in a unit of lot. Therefore, in the lithography process for a plurality of lots with the same product name and the same process name, it is possible to reduce the process offset of the exposure process every time a lot is changed, so that an increase in the process offset can be avoided.